Defects and structure of hydrogenated microcrystalline silicon films deposited by different techniques

Abstract

The development of structure and paramagnetic defects of microcrystalline silicon films prepared by plasma enhanced chemical vapour deposition at very high frequency (VHFPECVD), at radio frequency and in the high pressure, high power regime (RFPECVD) and by the hot wire CVD (HWCVD) are studied. The relationship between paramagnetic defects and structural configuration of μc-Si:H films obtained under deposition conditions near the amorphous-microcrystalline structural transition is investigated using results from electron spin resonance (ESR) such as spin density, g-value, ESR peak to peak line width Δ H pp, and crystalline volume fraction as calculated from Raman spectroscopy. Similar relationships between the structure transition from crystalline to amorphous and the density and spectral shape of paramagnetic defects are observed for all deposition methods. Low substrate temperatures and deposition conditions close to the transition to amorphous growth are found beneficial for low spin densities in accordance with the optimum growth conditions for high efficiency solar cells.